This invention relates to a multiplexer for a plurality of audio sources that may be used to feed an audio mixer, amplifiers, or recording devices.
The common practice of amplifying a musical concert involves feeding a plurality of microphones on the concert stage through their individual lines, which can extend to over a hundred feet, to a mixer located in the audience. At the mixer, the musical instruments and vocalists are then amplified, equalized and otherwise modified etc., to achieve optimum results in terms of audience effect, artist capability, musical quality and so forth.
Various problems arise when using long lines or cables from each microphone to the mixer, the first problem being the weight and expense of these cables which can amount to 100 pounds or more. Also, if one of these cables or its connections become damaged or badly worn, the quality of the transmitted signal will be impaired. In addition, source loading and signal attenuation become significant problems when using long microphone cables, even if the cable and its connections remain intact.
Another problem involves loss of recording fidelity because of non-uniform signal attenuation. Overall, desireable characteristics when transmitting an audio signal include high signal/noise ratio, wide bandwidth, low distortion, and a predictable signal output. If an audio signal is multiplexed, the sample frequency must be suppressed, and a fast sample time must be utilized. In the case of audio signals, the frequency response loss should not be affected by the cable.